This invention relates to new cycloaliphatic polycyclic diamines and to their use for the production of plastics, especially light-stable and weatherproof polyurethane plastics. Aliphatic and cycloaliphatic diamines are important intermediate products which are frequently used in industry for the production of plastics. They are in particular used as chain extenders, crosslinkers or even as intermediate products for the production of isocyanates in the manufacture of light-stable polyurethane plastics. Known aliphatic and cycloaliphatic diamines include, for example, 1,6-hexamethylene diamine; 2,2,4- and 2,4,4-trimethyl hexamethylene diamine; 1,4-diaminocyclohexane; 2,4- and 2,6-diamino-1-methyl cyclohexane; 1,3-diaminomethyl cyclohexane; 3-aminomethyl-3,5,5-trimethyl cyclohexylamine; 4,4'-diaminodicyclohexyl methane; and 3,3'-dimethyl-4,4'-diaminodicyclohexyl methane. These conventional amines, however, have numerous disadvantages. For example, the lower molecular weight (cyclo)aliphatic diamines have an appreciable vapor pressure so that the atmosphere may be heavily polluted by an amine odor. Problems are also involved in handling the relatively high molecular weight solid or semicrystalline amines, such as 1,6-hexamethylene diamine, 4,4'-diaminodicyclohexyl methane or 1,4-diaminocyclohexane (cis/transisomer mixture) since they have to be melted before processing. In this case, the amine vapors pollute the atmosphere to a particularly serious extent.
Another disadvantage lies in the processes for synthesizing the above-mentioned diamines, some of which are extremely complex. For example, 2,4- and 2,6-diamino-1-methyl cyclohexane or 4,4'-diaminodicyclohexyl methane are obtained by the nuclear hydrogenation of corresponding aromatic intermediate products.
Accordingly, there is a need for diamines which can be produced simply and economically, are liquid at room temperature and have a low vapor pressure. A new class of cycloaliphatic diamines which have these properties and which can be produced by a simple synthesis has now surprisingly been found.